PROJECT SUMMARY Pathologic ocular angiogenesis is the underlying mechanism of a variety of sight threatening diseases of the eye affecting a wide range of patients including premature infants and the elderly. Retinopathy of prematurity (ROP), proliferative diabetic retinopathy (PDR), and exudative age-related macular degeneration (wet AMD) are common causes of blindness in infants, working age, and the elderly respectively. These conditions are primarily characterized by aberrant neovascularization, or the formation of vascular membranes on top or below the retina. We performed transcriptome analysis of vascular endothelial cells (ECs) obtained from fibrovascular membranes (FVMs) from patients with PDR, and identified Runt-related transcription factor 1 (Runx1) as a gene that is upregulated in pathologic ocular angiogenesis. We subsequently showed that Runx1 mediated EC function, and that its inhibition leads to a reduction in aberrant angiogenesis in a mouse model of oxygen-induced retinopathy (OIR). Based on these data, we hypothesize that Runx1-mediated angiogenesis is an important mechanism for aberrant angiogenesis within the eye, and that Runx1 inhibition is a potential therapeutic modality for the treatment of a wide array of pathologic angiogenic diseases. To test this hypothesis, the following research aims are proposed: Aim 1. To determine the role of Runx1 in physiological and pathological angiogenesis using genetic models of Runx1 loss- and gain-of-function: Using inducible models of Runx1 loss- and gain-of-function (LOF/GOF), we will evaluate the role of Runx1 in both physiological and pathological angiogenesis. We will look at postnatal development of the retinal vessels, as well as pathologic angiogenesis using laser-induced choroidal neovascularization (CNV). Aim 2. To determine the downstream effectors of Runx1 transcriptional activity. Using transcriptome analysis, we propose to identify genes that are potentially regulated by Runx1 using human retinal microvascular endothelial cells and Runx1 LOF/GOF models. Using a combination of bioinformatics screening methodologies (gene ontology analysis, Runx1 regulatory sequence analysis, and comparison to our published human PDR transcriptomes) and in vitro validation of gene targets, we propose to identify the direct/indirect downstream mediators that regulate Runx1-mediated angiogenesis. Aim 3. To compare anti-Runx1 versus anti-VEGF treatment in genetic and inducible models of pathologic ocular angiogenesis. Anti-Runx1 therapy has potential benefits over anti-VEGF therapy. In this aim, we propose to compare anti-Runx1 versus anti-VEGF therapy alone or in combination using multiple models of angiogenesis: OIR, Akimba, and laser-induced CNV. Thus this aim will elucidate the translational potential of anti-Runx1 therapy for the management of such diseases as ROP, PDR, and wet AMD.